The present invention generally relates to the human performance, sports medicine and medical rehabilitation field. More specifically, the present invention relates to a method for fall prevention training using a dynamic perturbation platform to improve the study and research of the biomechanics of trip, slip, and laterally-directed postural disturbances by a person and the step recovery thereof. Additionally, the present invention relates to human performance, injury prevention and neuromuscular training using a dynamic perturbation platform to train step responses to anterior, posterior or laterally-directed postural perturbations. Additionally, the present invention relates to neuromuscular training around any body joint response to dynamic perturbations of the body joint or multiple body joints.
It is well known in the medical field that a slip or trip during walking or standing can lead to a fall and be a serious cause of injury. This is particularly problematic for elderly people where such injuries are a leading cause of mortality. It is well known that many of these injuries can be prevented or their severity lessened if the person uses an effective strategy and technique for responding to a fall situation. Therapeutic Interventions can reduce the likelihood of a fall from a disturbance event, such as a trip or slip incident. Exercise and physical training can be used to develop strength, balance and coordination. Also, the person's environment can be changed to remove obstacles and other hazards that can cause a slip or trip. Bars and hand rails can be provided to assist walking and standing. Padded garments can be worn by the person to reduce the injury caused by the slip or fall.
An alternative approach is to study why a person falls and train them to better recover from a slip or trip to avoid a fall by taking a corrective step response. Therefore, the biomechanics of a slip or fall can be studied to better understand clinically effective ways to prevent such falls due to a slip or trip. As part of the study and analysis of disturbance events, including slip and trip incidents, it is highly desirable to be able to monitor a slip or fall incident in a controlled environment to produce data that is usable for effective training to help persons adapt their strategy for responding to a slip or trip incident.
It is also well known in the medical field that dynamic stability of a body joint is important for injury prevention. The ligaments and tendons and musculature that cross body joints prevent excessive motion of the joint that leads to injury of the structures both within and surrounding the joint. The benefits of neuromuscular training are known to provide increased endurance, positional awareness, performance and reduction in injury risk.
Specifically with respect to the knee, neuromuscular training also increases dynamic knee stiffness, dynamic knee stability, and athlete agility. Human locomotion uses sensory information and motor reflex to modulate pre-programmed motor control patterns in order to adapt to unexpected changes in the external environment. Proprioceptive information is used to maintain postural and joint stability. In human locomotion there are major kinematic events where joint stability might be needed most. These events differ for walking and running. All around the body, joint stability is attributed to joint stiffness that occurs with co-contraction of antagonistic muscles around a joint. Increased joint stiffness is believed to resist sudden joint displacements more effectively reducing the incidence of joint subluxation.
More specifically, it is well known in the medical field that ligament and other soft tissue injuries are a significant problem among people who engage in cutting, jumping, and pivoting activities, particularly young athletes and women. One ligament that is often injured, for example, is the anterior cruciate ligament (ACL) in the knee. For ACL injured athletes, neuromuscular training has improved functional outcome and increased likelihood of return to previous activity levels with decreased likelihood of knee giving way episodes. Similar effects and results can occur following soft tissue injuries to other structures and joints in the body, and are not limited to the ACL.
Following ACL or other soft tissue injury, both surgical and non-surgical treatment options exist, with the ultimate goal of regaining dynamic joint stability, and in the case of the knee joint, normal knee kinematics, and symmetrical quadriceps strength between legs. These outcomes are critical for full return of dynamic knee function and returning to pre-injury activity levels, as well as for preventing additional injury to the cartilage and the meniscus in the knee which might lead to an increased likelihood of osteoarthritis (OA).
Laboratory research has demonstrated clinically relevant effects of perturbation of support surface training for both ACL-deficient (ACL-D) and ACL-reconstructed (ACL-R) populations, particularly in females. Currently, perturbation training systems and methods are limited to balance boards that are manually pushed or pulled by physical therapists, and may not simulate real-life or sport-specific perturbations. Specifically, balance boards do not allow for perturbations that occur during an actual step. The manual perturbation method does not allow for repeatable timing of perturbations at specific phases of the gait cycle, nor can the perturbations be delivered in less than 500 ms.
ACL injuries are extremely common, with approximately 100,000-250,000 ACL reconstructions being performed annually in the United States. While males comprise a majority of all ACL injuries females are at 3-6× greater risk of suffering an ACL rupture than males. Rehabilitation is time-consuming; time from injury to completing postoperative rehabilitation can range from a few months to a year or more, and surgical intervention does not ensure a return to previous activity levels. At an estimated cost of $17,000 per ACL reconstruction and physical therapy services, expenses for this injury may exceed $1 Billion annually in the United States alone.
The ACL plays a principal role in maintaining normal knee function and stability. Quadriceps strength deficits and ACL rupture independently increase the likelihood of developing knee osteoarthritis (OA). ACL injury often leads to knee instability, quadriceps weakness, gait deviations, and post-traumatic OA. Aberrant movement and abnormal muscular strategies are common in the ACL-deficient athlete. Snyder-Mackler and colleagues developed and validated a functional screening examination as a clinical tool to identify those who have the potential to compensate well for the injury (potential-copers). Non-candidates, or non-copers, were classified by their poor functional performance and episodes of knee instability. Recurrent give way episodes of the ACL deficient knee in non-copers are likely due to their inability to stabilize their injured knee with appropriate muscle activity. Rudolph et al. defined the neuromuscular behaviors of ACL deficient athletes, and found an ineffective knee stiffening strategy characteristic of non-copers. Non-copers excessively co-contract their thigh and hamstring muscle and truncate their knee motion which may further exacerbate the alterations in joint loading and cause degenerative changes to the underlying cartilage. Persons who present with a combination of aberrant gait patterns, quadriceps weakness, and knee instability in response to an ACL rupture are at significantly increased risk of developing post-traumatic knee OA. Therefore, the importance of restoring normal gait kinematics and kinetics in this population has been underscored by many research groups.
Quadriceps weakness and knee instability can also lead to a knee stiffening strategy in an attempt to improve stability during dynamic activities, such as walking, jogging, stair climbing, and balancing on one limb. This strategy is used predominantly by athletes who are non-copers. Hartigan et al. demonstrated that perturbation training was able to restore symmetric knee excursions in this cohort, something that was not achieved by strength training alone. Again, this perturbation training was performed manually.
Clinical rehabilitation paradigms for non-operative treatment and post-operative rehabilitation following ACL rupture focus on reducing joint effusion, increasing knee range of motion, increasing quadriceps and hamstring muscle strength, functional activity education and training, agility training, and protective bracing. However, these approaches may only be successful for patients that are more sedentary or are willing to modify their physical activity levels. Common clinical techniques used during rehabilitation after ACL reconstruction are often limited to strength training, task-specific exercises, and static balance exercises. For athletes, proper coordination of muscle activity is also critical for improving dynamic knee stability and ultimately, sport performance.
After ACL injury, the quadriceps and hamstrings have diminished ability to dynamically stabilize the knee due to disruption of the mechanoreceptors in and around the knee joint. Task-specific manual perturbation training has been shown to enhance the restoration of dynamic stability in ACL deficient patients. Factors that are modulated during perturbation training include predictability, speed, direction, amplitude, and intensity of the perturbation. Snyder-Mackler and colleagues combine progressively challenging manual perturbation training together with sport-specific task training in order to achieve improvements in dynamic knee stability. Snyder-Mackler and other researchers published the results of their studies and have demonstrated the following:                Superior return to functional activity in potential copers when compared to standard rehab programs (e.g. strength training). 93% of patients using manual perturbation training returned to high-level activity without episodes of giving way. In contrast, only 50% of those who received traditional therapy returned to high-level activity.        Patients undergoing perturbation training increased their likelihood of success (i.e. no episodes of knee giving way) by 4.9× when compared to standard treatments, including strength and agility training.        Improved dynamic knee stability in ACL deficient patients through improved neuromuscular changes.        Increased Lysholm Knee Rating Scale scores compared to subjects who received standard strength training rehabilitation.        Normal quadriceps and hamstring activations and increased active stiffness. These changes may prophylactically reduce the risk of biomechanical strain injury in high-risk populations.        Manual perturbation training significantly improved lower leg dynamic muscle control in healthy young athletes. Young women responded favorably to perturbation training by mitigating their quadriceps dominance and activating their hamstrings earlier in stance, thus restoring healthier muscle activation patterns.        Manual perturbation training in conjunction with strength training improved dynamic knee stability, knee range of motion during midstance, and limb symmetry compared to strength training alone.        
While manual perturbation paradigms are effective at resolving aberrant neuromuscular strategies in ACL-deficient individuals, the time required to administer the treatment may not allow the therapist time to address other patient impairments. Manual perturbation training does not address the idea of providing the perturbation during the walking cycle or while running. Additionally, manual perturbation training may not allow for timed perturbations at specific phases of the gait cycle, or at specific joint positions, velocities or joint forces. Manual perturbation do not allow for timed and controlled perturbations at specific velocities of a given joint.
Conversely, the present invention overcomes the limitations of manual perturbation methods. In the present invention, perturbations can be triggered manually, or, when desired, on a timed basis or other pre-set schedule. The timing of perturbations can be based on intrinsic physiologic factors, such as phase of the gait cycle, position, velocity or acceleration of a limb or joint. The timing of perturbations based on specific phases of gait, perturbation and automatic speed adjustments can be based on the timing and phasing of braking and propulsion of the limb being monitored.
Additionally, the timing of perturbations can be based on extrinsic factors. There exists relationships among neuromuscular timing and external cues or triggers. Existing systems such as Nike+, a product of Nike, Inc., modify target exercise parameters based on music selected. Alternatively, it is possible to modulate the speed, pitch, volume, beat, and other rhythmic patterns of music played or presented to a user as a function of the exercise being performed or prescribed. In a similar fashion, visual stimuli such as video presentations or tactile stimuli or other external stimuli can be used in either an excitatory or feedback mode in conjunction with neuromuscular training. Such interactions between external stimuli and neuromuscular training specifically are lacking in the prior art.
The present invention can be used to address and prevent a wide range of joint related diseases and injuries, such as but not limited to osteoarthritis and ankle sprains. The present invention is not limited to preventing joint-related diseases and injuries in the lower extremity. There is a also a need to be able to provide controlled perturbations to portions of the body other than those in the lower extremity. For example, there is a need to be able to deliver controlled perturbations to areas of the upper body, such as the elbow, wrist or shoulder for the prevention of disease and injury to those regions.
In view of the foregoing, there is a need for a system that can accurately simulate a slip or tripping incident. There is a need for a system that can measure the biomechanics of a slip or tripping incident to further assist a person to better respond to the incident to avoid a fall. There is a further need for an apparatus that is well-suited to measure such biomechanics. There is a need for an apparatus that can simulate various trip and slip scenarios that could lead to a fall so an appropriate response can be developed. There is a need for an apparatus and system that can better train a person to avoid a fall following a trip or slip incident. Moreover, there is a need for a method for fall prevention training to better prepare a person for a disturbance event, including, a slip, trip or fall, to avoid injury or death.
In view of the foregoing, there is a need for a system that can provide task-specific, neuromuscular, dynamic perturbation training to prevent injury to the soft tissues surrounding body joints There is a need for a system that provides perturbations that induce joint instability that requires a neuromuscular response to retain, maintain or retrain intrinsic body joint stabilization There is a need for a system that provides task-specific, neuromuscular, dynamic perturbation training to prevent the development and progression of osteoarthritis and other joint-related diseases. There is a need for a system to provide perturbations during the stance phase of the gait cycle during locomotion. There is a need for a system to provide perturbations during the different phases of stance in the gait cycle to elicit a specific joint response. There is a need for a system to provide perturbations that are controlled and triggered by detecting the braking, midstance and propulsion phases of control for a given joint. There is a need for a system to provide perturbations to a joint at a preferred kinematic position, velocity, or loading condition to elicit and train a specific joint response. There is a need for a system to provide modulation of the stretch reflex to prevent ankle sprains. There is a need for a system that detects the different phases of the gait cycle, including but not limited to the stance phase, which also includes the braking, midstance, and propulsion phase, and which provides a trigger for delivering the perturbation. There is a need for a system that provides aperiodic perturbations to challenge and train the joint response to perturbations that occur during daily living or during sporting activity. There is a need for a system to provide perturbations during athlete training or physical therapy where the perturbations are delivered automatically, and in some cases repeatedly, without any manual intervention from another individual or medical provider.
There is a need for a system that can provide controlled perturbations to any part of the body, including the elbow, wrist and shoulder to help train response to such perturbations and prevent disease and injury to those regions. There is a need for a system that can deliver perturbations very quickly and in an automated and controlled fashion to any part, portion or region of the body.
There is a need for a system to provide perturbations during the stance phase of the gait cycle that are synchronized with musical cues and other external stimuli. There is a further need for a system to provide perturbations of varying magnitude, direction and duration that are generated automatically based on the timing of music driving the system. There is a need for a system that selects music to be presented to a user based on the perturbation profile selected for a given neuromuscular training activity There is a need for a system to provide perturbations that stimulates and trains braking and propulsion control for the joint.